Regensburg 2025 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 13: Heterostructures, Interfaces and Surfaces

HL 13.5: Talk

Monday, March 17, 2025, 17:45–18:00, H17

Understanding Local Charge Transport Using Advanced Kelvin Probe Force Microscopy — •Sven Erik Doll, Sergej Levashov, Nina Miller, and Johanna Eichhorn — Department of Physics, TUM School of Natural Sciences, Technical University of Munich, Am Coulombwall 4, 85748 Garching, Germany

Efficient photosystems for solar-to-chemical energy conversion are often based on nanostructured semiconductor architectures. In these material systems, the nanoscale properties frequently dominate the performance at the macroscale. Therefore, local understanding of their charge transfer and transport properties is decisive for optimizing their efficiency and stability.

To this end, we use Kelvin probe force microscopy (KPFM) in a controlled atmosphere to spatially resolve band bending, charge accumulation, and local variations of the generated surface photovoltage. However, analyzing nanostructured materials with complex morphologies is not trivial since topographic crosstalk can dominate the results. To overcome these limitations, we combine a commercial AFM with an external Lock-In amplifier to enable dual-frequency and heterodyne KPFM measurements with improved resolution and sensitivity compared to conventionally frequency-modulated and amplitude-modulated KPFM modes. Here, we compare different KPFM modes and highlight the importance of careful imaging and data analysis to reveal insights into local semiconductor material properties at grain boundaries or different facets.

Keywords: AFM; KPFM; Heterodyne KPFM; Thin Films